In the semiconductor field, integrated circuits are manufactured from large pieces of semiconductor material commonly known as wafers. The wafers have deposited on them various layers of conducting and non-conducting material. These layers are each separately deposited on the wafer as it is built up in a step-by-step process. The layers can be applied to the wafer using any one of several methods which are well known in the art.
One of these well-known deposition methods involves surrounding the wafer with a gas containing the desired material to be deposited on the wafer. The wafer and the gas are oppositely charged, and the material is electrically attracted to the wafer. This process is usually carried out within a sealed tube. One disadvantage of this process is that all of the material in the gas does not necessarily become attached to the wafer. As a result, some of the material settles onto the bottom of the tube. This extra material can later become mixed in with the material in the gas. The amount of suspended material is carefully controlled so that a precise amount will be evenly deposited on the wafer. Any accumulation of material within the tube is highly undesirable as it may eventually become depositised on the wafers. To prevent this accumulation, the tubes must be periodically removed and cleaned. However, removal of the tubes results in a loss of production time, thus adding to the cost of manufacturing the wafers. Also, the tubes used in the semiconductor manufacturing process are often made of a brittle material, such as quartz. When a quartz tube is removed, there is a risk that the tube may be broken. Moreover, the process of depositing a substrate material onto the wafers is usually conducted at a high temperature. Additional down time and cost are incurred in allowing the tube to cool before it is cleaned and in reheating the tube before it can be used again.